ndt-users list created

[Richard Carlson <>]

Hi Phil;

Right off the bat I notice a big change in the reported RTT.  In the first 
test it's 211 msec so the 64 KB buffer limits things to 2.6 Mbps.  In the 
second test the RTT dropped to 64 msec (or 7.8 Mbps).  You might want to 
try running some pings to various boxes to see where the delay is being 
introduced.  It could be a time of day issue with more users causing more 
delays.

Rich

At 12:08 PM 9/14/2005, Phil Reese wrote:
> I'm starting to think I'm calling WOLF, but here are more data points.
>
> Last night I ran the NDT test and got the following info:
> running 10s outbound test (client to server) . . . . . 667.46Kb/s
> running 10s inbound test (server to client) . . . . . . 2.20Mb/s
>
> CurCwnd: 102200
> CurRwinRcvd: 65535
> Duration: 10088170
> Sndbuf: 223232
>
> estimate = 52.78 based on packet size = 11Kbits, RTT = 211.03msec, and 
> loss = 1.0E-6
> The theoretical network limit is 52.78 Mbps
> The NDT server has a 218.0 KByte buffer which limits the throughput to 
> 8.07 Mbps
> Your PC/Workstation has a 63.0 KByte buffer which limits the throughput to 
> 2.36 Mbps
> The network based flow control limits the throughput to 3.69 Mbps
>
> Client Data reports link is 'T1', Client Acks report link is 'T1'
> Server Data reports link is 'OC-48', Server Acks report link is 'Ethernet'
>
> DSLReports at the same time:
> Your download speed : 8652754 bps, or 8449 kbps.
> A 1056.2 KB/sec transfer rate.
> Your upload speed : 708497 bps, or 691 kbps.
>
>
> Then this morning, early, running in the same browser window from the test 
> of last night (first time this has given the expected results in several 
> weeks):
> running 10s outbound test (client to server) . . . . . 733.66Kb/s
> running 10s inbound test (server to client) . . . . . . 7.33Mb/s
>
> CurCwnd: 48180
> CurRwinRcvd: 65535
> Duration: 10065985
> Sndbuf: 223232
>
> estimate = 7.02 based on packet size = 11Kbits, RTT = 63.99msec, and loss 
> = 6.1529E-4
> The theoretical network limit is 7.02 Mbps
> The NDT server has a 218.0 KByte buffer which limits the throughput to 
> 26.61 Mbps
> Your PC/Workstation has a 63.0 KByte buffer which limits the throughput to 
> 7.81 Mbps
> The network based flow control limits the throughput to 12.18 Mbps
>
> Client Data reports link is 'Ethernet', Client Acks report link is 'T1'
> Server Data reports link is 'OC-48', Server Acks report link is '10 Gig'
>
> DSLReports at the same time:
> Your download speed : 8348353 bps, or 8152 kbps.
> A 1019 KB/sec transfer rate.
> Your upload speed : 712115 bps, or 695 kbps.
>
>
> I'm back to thinking that something odd is happening within Comcast's -- 
> Stanford's network over time.  Other thoughts?
>
> Is there other info I might provide?
>
> Phil

------------------------------------



Richard A. Carlson                              e-mail: 

Network Engineer                                phone:  (734) 352-7043
Internet2                                       fax:    (734) 913-4255
1000 Oakbrook Dr; Suite 300
Ann Arbor,  MI  48104